Bandwidth Broadening of MEMS Vibration Energy Harvesters by Voltage-boost Rectifier Circuit

This paper presents a methodology to extend the working bandwidth of vibration energy harvesters (VEHs) by using a voltage-boost rectifier (VBR) circuit. The VBR circuit rectifies small ac voltages of MEMS VEHs and boosts them to a dc voltage sufficient for the operation of the subsequent circuitry. The proposed system using the VBR circuit can work regardless of the VEH type. Also, the VBR circuit can be monolithically integrated with CMOS LSI without using other external components. The developed VBR circuit is experimentally evaluated using a MEMS VEH and successfully delivers boosted dc voltages even when the input ac amplitude is below 0.4 V in the frequency range (<1 kHz) of environmental vibrations. We confirm that the working bandwidth can be increased by employing the VBR circuit compared with the use of conventional diode rectification.